/*
 * Copyright (c) 2000-2010 Marc Alexander Lehmann <schmorp@schmorp.de>
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#include "lzfP.h"

#if AVOID_ERRNO
#define SET_ERRNO(n)
#else
#include <errno.h>
#define SET_ERRNO(n) errno = (n)
#endif

#if USE_REP_MOVSB /* small win on amd, big loss on intel */
#if(__i386 || __amd64) && __GNUC__ >= 3
#define lzf_movsb(dst, src, len)                                                                   \
    asm("rep movsb" : "=D"(dst), "=S"(src), "=c"(len) : "0"(dst), "1"(src), "2"(len));
#endif
#endif

unsigned int lzf_decompress(const void *const in_data, unsigned int in_len, void *out_data,
                            unsigned int out_len) {
    u8 const *ip = (const u8 *)in_data;
    u8 *op = (u8 *)out_data;
    u8 const *const in_end = ip + in_len;
    u8 *const out_end = op + out_len;

    do {
        unsigned int ctrl = *ip++;

        if(ctrl < (1 << 5)) /* literal run */
        {
            ctrl++;

            if(op + ctrl > out_end) {
                SET_ERRNO(E2BIG);
                return 0;
            }

#if CHECK_INPUT
            if(ip + ctrl > in_end) {
                SET_ERRNO(EINVAL);
                return 0;
            }
#endif

#ifdef lzf_movsb
            lzf_movsb(op, ip, ctrl);
#else
            switch(ctrl) {
            case 32:
                *op++ = *ip++;
            case 31:
                *op++ = *ip++;
            case 30:
                *op++ = *ip++;
            case 29:
                *op++ = *ip++;
            case 28:
                *op++ = *ip++;
            case 27:
                *op++ = *ip++;
            case 26:
                *op++ = *ip++;
            case 25:
                *op++ = *ip++;
            case 24:
                *op++ = *ip++;
            case 23:
                *op++ = *ip++;
            case 22:
                *op++ = *ip++;
            case 21:
                *op++ = *ip++;
            case 20:
                *op++ = *ip++;
            case 19:
                *op++ = *ip++;
            case 18:
                *op++ = *ip++;
            case 17:
                *op++ = *ip++;
            case 16:
                *op++ = *ip++;
            case 15:
                *op++ = *ip++;
            case 14:
                *op++ = *ip++;
            case 13:
                *op++ = *ip++;
            case 12:
                *op++ = *ip++;
            case 11:
                *op++ = *ip++;
            case 10:
                *op++ = *ip++;
            case 9:
                *op++ = *ip++;
            case 8:
                *op++ = *ip++;
            case 7:
                *op++ = *ip++;
            case 6:
                *op++ = *ip++;
            case 5:
                *op++ = *ip++;
            case 4:
                *op++ = *ip++;
            case 3:
                *op++ = *ip++;
            case 2:
                *op++ = *ip++;
            case 1:
                *op++ = *ip++;
            }
#endif
        } else /* back reference */
        {
            unsigned int len = ctrl >> 5;

            u8 *ref = op - ((ctrl & 0x1f) << 8) - 1;

#if CHECK_INPUT
            if(ip >= in_end) {
                SET_ERRNO(EINVAL);
                return 0;
            }
#endif
            if(len == 7) {
                len += *ip++;
#if CHECK_INPUT
                if(ip >= in_end) {
                    SET_ERRNO(EINVAL);
                    return 0;
                }
#endif
            }

            ref -= *ip++;

            if(op + len + 2 > out_end) {
                SET_ERRNO(E2BIG);
                return 0;
            }

            if(ref < (u8 *)out_data) {
                SET_ERRNO(EINVAL);
                return 0;
            }

#ifdef lzf_movsb
            len += 2;
            lzf_movsb(op, ref, len);
#else
            switch(len) {
            default:
                len += 2;

                if(op >= ref + len) {
                    /* disjunct areas */
                    memcpy(op, ref, len);
                    op += len;
                } else {
                    /* overlapping, use octte by octte copying */
                    do
                        *op++ = *ref++;
                    while(--len);
                }

                break;

            case 9:
                *op++ = *ref++;
            case 8:
                *op++ = *ref++;
            case 7:
                *op++ = *ref++;
            case 6:
                *op++ = *ref++;
            case 5:
                *op++ = *ref++;
            case 4:
                *op++ = *ref++;
            case 3:
                *op++ = *ref++;
            case 2:
                *op++ = *ref++;
            case 1:
                *op++ = *ref++;
            case 0:
                *op++ = *ref++; /* two octets more */
                *op++ = *ref++;
            }
#endif
        }
    } while(ip < in_end);

    return op - (u8 *)out_data;
}
